FIG. 1 depicts a side view of portion of a conventional magnetic recording disk drive 10. FIG. 1 is not to scale and only portions of the conventional disk drive 10 are shown. The conventional disk drive 10 includes a disk 12 and a conventional slider 20 that is typically attached to a suspension (not shown). In operation, the slider 20 flies a distance, known as the fly height h, above the conventional disk 12 while the conventional disk 12 spins. Thus, the slider 20 and disk 12 are in relative motion. An air bearing is formed between the conventional disk 12 and the slider 20 at the air-bearing surface (ABS) 22 due to this relative motion. Using magnetic recording write and read transducers on the slider 20, data may be written to and read from portions of the conventional disk 12.
The current trend in magnetic recording is toward increasing the areal storage density of magnetic disk 12. This may be achieved in part by reducing the spacing between the slider 20 and the conventional disk 12. Thus, the fly height, h, may be desired to be reduced. Optimization of the spacing between the conventional slider 20 and the conventional disk 12 for the particular disk drive 10 is also desired. The optimization may, for example, be carried out to ensure that despite the decreased fly height, the slider 20 does not contact the conventional disk 12 while the disk 12 is spinning. As part of this optimization, account is desired to be taken of variations in the spacing. For example, portions 23 of the ABS 22 of the slider 20 may protrude during operation. This protrusion may be due to local heating of the slider 20, for example when a current is driven in the slider 20. Such protrusions 23 further reduce the spacing between portions of the conventional slider 20 and the conventional disk 12.
FIG. 2 depicts a conventional method 50 for measuring variations of the ABS of the conventional slider 20. The conventional method 50 is described in the context of the slider 20 and disk drive 10. The slider 20 is accessed before being placed in the disk drive 10 or is removed from the disk drive 10, via step 52. Thus, the slider 20 is separate from the remaining components of the conventional disk drive 10 during measurements in the method 50.
Portions of the conventional slider 20 are heated, via step 54. Step 54 may be performed, for example, by driving a current through the read and/or write transducer in the conventional slider 20. Thus, thermal protrusions analogous to the thermal protrusion 23 may be formed. The thermal protrusions of portions of the slider 20 are measured, via step 56. Step 56 may, for example, be carried out using techniques such as optical profilometry and/or atomic force microscopy. Alternatively, the temperature of regions of the ABS may be measured in step 56, and the thermal protrusion inferred.
Although the conventional method 50 functions, the information provided may have limited utility. Inferring the protrusion from thermal data may require a significant amount of interpretation and have limited spatial resolution. Profilometry may require equal wear to be assumed and may not be capable of providing a deformation profile under normal operating conditions. Other conventional techniques may have analogous drawbacks. Further, as discussed above, the conventional slider 20 is typically separate from other components in the conventional disk drive 10 during measurement in step 56. The thermal protrusions measured in the method 50 may differ from those that might occur in the conventional disk drive 10. Thus, an accurate determination of the contours of the ABS 22 may not be obtained. Without an accurate determination of the profile of the ABS 22, optimization of the distance between the slider 20 and disk 12 may be difficult.
Accordingly, what is needed are improved methods and systems for mapping the profiles of the ABS in magnetic recording disk drives.